Zhonghua Minguo wei sheng wu ji mian yi xue za zhi = Chinese journal of microbiology and immunology最新文献

N-acetyltransferase activities with p-aminobenzoic acid and 2-aminofluorene were determined in Hymenolepis nana, a cestode found in the intestine of the Sprague-Dawley rats. The N-acetyltransferase activity was determined using an acetyl CoA recycling assay and high pressure liquid chromatography. The N-acetyltransferase activities from a number of Hymenolepis nana whole tissue homogenizations were found to be 2.83 +/- 0.31 nmole/min/mg for 2-aminofluorene and 2.07 +/- 0.24 nmole/min/mg for p-aminobenzoic acid. The apparent Km and Vmax were 1.06 +/- 0.38 mM and 8.92 +/- 1.46 nmol/min/mg for 2-aminofluorene, and 2.16 +/- 0.19 mM and 12.68 +/- 2.26 nmol/min/mg for p-aminobenzoic acid. The optimal pH value for the enzyme activity was pH 8.0 for both substrates tested. The optimal temperature for enzyme activity was 37 degrees C for both substrates. The N-acetyltransferase activity was inhibited by iodacetamide. At 0.25 mM iodacetamide the activity was reduced 50% and 1.0 mM iodacetamide inhibited activity more than 90%. Among a series of divalent cations and salts, Fe2+, Ca2+ and Zn2+ were demonstrated to be the most potent inhibi-tors. Among the protease inhibitors, only ethylenediaminetetraacetic acid significantly protected N-acetyltransferase. Iodoacetate, in contrast to other agents, markedly inhibited N-acetyltransferase activity. This is the first demonstration of acetyl CoA:arylamine N-acetyltransferase activity in a cestode and extends the number of phyla in which this activity has been found.

The ID90 or ID50 values of acyclovir for the herpes simplex virus strains isolated in VGH-Taipei were determined by plaque reduction method. Twenty HSV isolates of 1980's (1980-1985) and thirty of 1990's (1990-1995) were subjected to plaque reduction assay for susceptibility test to acyclovir. There were fifteen HSV isolates of 1990's whose ID90 were higher than those of 1980's, indicating a trend of more acyclovir resistant isolates in 1990's.

Vibrio parahaemolyticus is a causative bacterium of food poisoning, and the haemolysin produced by this organism has been considered as one of the important virulence factors. In order to understand the pathogenic mechanism of this bacterium, the characteristics of haemolysin from Vibrio parahaemolyticus isolated from Taiwan were studied. One of the clinical strains, V. parahaemolyticus No.93, presents a weak hemolytic zone on 7% NaCl-Wagatsuma medium. The DNA hybridization results show that V. parahemolyticus has neither tdh nor trh gene. V. parahaemolyticus No.93 shows obviously hemolytic zone on 3%-NaCl Wagatsuma medium (human blood). The crude extracellular protein of V. parahaemolyticus No. 93 was evaluated for its heat tolerance and enzyme activities by media assay. The results show that this crude extracellular protein is thermolabile. The crude extracellular protein of V. parahaemolyticus No.93 was analyzed on 10% SDS-PAGE and an apparent band of 64 kDa protein was observed. Furthermore, the crude extracellular protein was analyzed by running gelatin-SDS-PAGE and hemoglobin-SDS-PAGE, and three clear zones on 62 kDa, 52 kDa and 41 kDa were observed on both SDS-PAGEs. Thus we propose that the crude extracellular protein of the V. parahaemolyticus No.93 can degrade gelatin as well as hemoglobin. Whether these protease being the virulence factors of Vibrio parahaemolyticus No.93 needs to be further studied.

There is no plaque case report in Taiwan since 1952. However, it is necessary to set up a laboratory system to investigate the distribution of Yersinia pestis in the natural environment to implement the public policy for preventing plague. Besides the traditional methods; e.g. culture, microscopic observation, biochemical characteristics, anti-F1 antigen detection by slide agglutination, immunofluorescence, and phage lytic assay, PCR was used as rapid screening test in our study. These laboratory methods were used to examine whether the flea samples harvested in King-Men island carry Y. pestis. The results showed that the flea index per mouse was high but no Y. pestis was detected in the fleas.

Candida albicans is a pathogenic yeast. Two sets of universal primers were used for specific identification of Candida albicans with PCR-amplified ribosomal DNA internal transcribed spacers (ITS). Among the species of Candida, the amplified ITSI and ITSII of DNA fragments were similar in size. The PCR product was purified and labeled with digoxigenin and used as DNA probe in the detection with target DNA of Candida albicans by hybridization. Two sets of specific primers (CA1 and CA2 to amplify ITSI, CA3 and CA4 to amplify ITSII) were designed by alignment of ribosomal ITS sequence of pathogenic Candida albicans with other species to detect C. albicans by PCR. The sensitivity of PCR using the specific primers to detect pure culture of C. albicans was 0.1 ng (about 10(3)-10(4) cells). If the yeast cells were mixed with two other strains, there was a 10-fold decrease in sensitivity (1 ng or 10(4)-10(5) cells) under the same PCR conditions.

From July 1994 through June 1996, 28 strains of Escherichia coli were isolated from 1,260 patients with acute diarrhea. These strains were further differentiated with serotypes and virulence factors. Enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enterohemorrhagic E. coli (EHEC), and enteroinvasive E. coli (EIEC) were accounted for 53.6 (15 of 28 strains), 28.6 (8 of 28), 10.7 (3 of 28) and 7.1% (2 of 28), respectively. Therefore, ETEC and EPEC are playing an important role in food-borne illness in Taiwan. Escherichia coli O157:H7, a new emerging pathogen of food-borne disease, has not been isolated in this study.

Carcinogenesis is a multi-process event that has been characterized both by activation of cellular oncogenes and by loss of function of tumor suppressor genes. However, no systemic study has been performed to understand the involvement of oncogenes and tumor suppressor genes in the oncogenesis of nasopharyngeal carcinoma (NPC). Differential display was performed to identify genes specifically expressed in normal nasal epithelial cells or NPC cell line HONE-1. Using Ltk3 and T11CA as primers, a 379-bp cDNA fragment (CN3) obtained from normal nasal epithelial cells was able to show specificity by northern blot analysis. A 3.5-kb mRNA was detected in normal nasal epithelial cells but not in NPC cell line HONE-1 by using 32P-end-labeled CN3 fragment as a probe. Sequence analysis of the 379 bp cDNA fragment indicated unique sequences from nts 1 to 230. Nts 231 to 379 are Alu-like sequences. Northern blot analysis using 32p-labeled PCR product amplified from nts 36 to 222 of CN3 cDNA fragment was also able to detect the 3.5-kb mRNA in normal nasal epithelial cells but not in HONE-1 and two other NPC cell lines NPC-TWO1, NPC-TWO4.

Several microbes were isolated from the contaminated fuel-oil in Taiwan and the microbial corrosion of aluminum alloy A356-T6 was tested by MIL-STD-810E test method. Penicillium sp. AM-F5 and Cladosporium resinac ATCC 22712 had significant adsorption and pitting on the surface of aluminum alloy, Pseudomonas acruginosa AM-B5 had weak adsorption and some precipitation in the bottom, and Candida sp. AM-Y1 had the less adsorption and few cavities formation on the surface. pH of the aqueous phase decreased 0.3 to 0.7 unit for 4 months of incubation. The corrosion of aluminum alloy was very significant in the cultures of Penicillium sp. AM-F2, Penicillium sp. AM-F5 and C. resinac ATCC 22712. The major metabolites in the aqueous phase with the inoculation of C. resinac were citric acid and oxalic acid, while succinic acid and fumaric acid were the minors.

A new plating medium, shrimp blood agar, was developed by using the haemolymph of shrimp plus 200 ppm rose bengal as the substrate. The colorless shrimp haemocytes were dyed by rose bengal to red. On the present agar, the hemolytic bacteria strain may show a clear zone surrounding the bacterial colony. The result on hemolysis of 45 bacteria representing 12 genera isolated from aquaculture environments against shrimp blood agar and sheep blood agar was also evaluated. There are 11 strains with different results. The study showed that, with the aim of screening the hemolytic bacteria to shrimp, shrimp blood agar might reveal a relatively quick and accurate results than that of sheep blood agar.

From 1983 through 1993, 786 strains of Vibrio parahaemolyticus were collected from food-borne disease outbreaks and sporadic cases of diarrheal illness in northern Taiwan, involving 42 K-serotypes. Five top leading serotypes were K8 (36.8%), K15 (10.8%), K12 (8.7%), K56 (7.9%) and K63 (4.7%). However, a variation of K-serotypes was found during this study period. From 112 food-borne outbreaks associated with this microorganism, only 54 (48.2%) outbreaks were caused by a single serotype, while 58 (51.8%) were caused by multiple K-serotypes. Numbers of outbreaks caused by two, three and more than three K-serotypes were 29 (26%), 16 (14.2%), and 13 (11.6%), respectively. In a special outbreak, eight K-serotypes was found. Outbreaks caused by party caterers were most frequently associated with multiple K-serotypes.